Meanwhile, authorities also said that the death toll might rise, as hundreds of people are still missing in Sonoma County.

The sheriff’s spokeswoman, Harris said authorities have located 110 people that were reported missing, but that about 300 still remain unaccounted for.

Daniel Berlant, assistant deputy director for Cal Fire, said on Wednesday, “This has been one of the deadliest weeks for fires that we’ve experienced in recent time. And a lot of that has to do with the fact that the fires ignited overnight. Many people were asleep when the fire started. Getting them evacuated was an extreme challenge for rescue crews.”

Tubbs and Atlas, the two biggest wine-country fires, that began in Napa County, expanded overnight.

According to Cal Fire, the fires have already spread across a combined 70,000 acres by Wednesday morning.

Over the past two days, the fast-moving flames have swept through densely populated neighbourhoods and have caused residents to flee from homes in the middle of the night as smoke filled their rooms.

Officials have warned that the sharp northern wind, known as a Diablo, would return, allowing only a brief window for firefighters to carve clearings in place to stop the fires from spreading to vulnerable populated areas.

The National Weather Service is expecting “red-flag” conditions, including wind gusts up to 40 mph, to remain until Thursday in the North Bay Area.

Officials have said that higher winds could hamper efforts to contain the fires over the next few days.

Weary firefighters attempted to control the fires on the front lines on Wednesday morning, as dozens of fire crews from cities as far away as Bakersfield, more than 300 miles to the south, were briefed on the deteriorating conditions.

So far, from seven counties north of San Francisco, over 25,000 people have fled homes, filling dozens of shelters that state officials had hoped to consolidate in the coming days.

In Sonoma County, 5,000 people have taken refuge in 36 shelters as of Wednesday morning.

During an afternoon news conference, Cal Fire Chief Ken Pimlott said, “These fires came down into neighbourhoods before anyone knew there was a fire in many cases. This is just pure devastation and it’s going to take us a while to get out and comb through all of this.”

On Tuesday, based on the scope of the damage, President Donald Trump approved federal emergency assistance to California, agreeing to a request made by Gov. Jerry Brown (D).

Vice President Mike Pence made the declaration during a visit to the state’s Office of Emergency Services near Sacramento that would provide immediate funds for debris clearing and supplies for evacuation centres, among other aid.

Brown said in a statement, “I appreciate the fast response from the President.”

The cause of the fires, which has raged through over 170,000 acres in the following days, remains unknown and likely to remain so for some time.